Embodiments herein generally relate to printing device and media trays, and relate more specifically to a media tray with vibrating projections that help prevent multiple sheets from being drawn out of the media tray.
Coated and uncoated stocks of printing media (e.g., paper, transparencies, cardstock, plastic sheets, etc.) sometimes have an issue with sheet separation when being drawn from the media tray into the printing device. The chemical properties of the coatings on the media and the weight of the media stack make it very difficult for sheets to separate from each other. In addition, humidity creates more problems with certain types of media.
One conventional way to separate sheets with a vacuum feeder is to blow ambient or heated air into the side of the stack for initial lift and separation of sheets. Vacuum is applied to the feeder housing to acquire the uppermost sheet to the feed position by using a vacuum plenum that can have compound angled surfaces to bend or flex in a manner that should cause gaps in the lead edge of multiple acquired sheets. Air pressure directed into the gaps, created by the vacuum plenum, can provide the final separation technique.
The embodiments herein comprise complete printing devices, or simply single modules of a printing device (e.g., a single paper tray) and are specifically directed to electrostatographic and xerographic devices. Therefore, some embodiments herein comprise a complete printing device that includes a printing media transport adapted to move printing media within the apparatus, a printing media input positioned at a first end of the printing media transport and a printing media output position at a second end of the printing media transport. A marking station is positioned within the apparatus adjacent to the printing media transport, wherein the marking station is adapted to form print markings on the printing media.
Embodiments herein supply a module to the foregoing structure that comprises a media tray positioned at the printing media input. The printing device includes a media mover (such as a roller, vacuum belt, etc.) positioned adjacent the media tray and also includes a controller operatively connected to the support structure and to the media mover. The media tray is adapted to be positioned next to the media mover so as to allow the media mover to contact the top sheet of the sheets of media.
The media tray has at least a bottom and two sides positioned along edges of the bottom. The media tray is adapted to hold sheets of media. The bottom comprises openings, and projections (tampers) extend through the openings in the bottom of the media tray. The projections comprise elongated structures having rounded or flattened ends. The projections extend through the openings enough to touch the bottom sheet of the sheets of media. In some embodiments, the support structure is adapted to move the projections through the openings different distances depending upon characteristics of the sheets of media, as indicated by the controller.
Further, at least one vibrating support structure is positioned on an opposite side of the bottom from the sheets of media (e.g., below the media tray). The support structure is connected to the projections in such a manner so as to vibrate the projections. More specifically, the controller is operatively connected to the vibrating support structure, and the controller is adapted to activate the vibrating support structure concurrently with the media mover. Thus, the support structure is adapted to vibrate the projections sufficiently to transfer vibrations from the bottom sheet to the top sheet to aid the media mover in removing only the top sheet and not any sheets adjacent to the top sheet (such as the second sheet in the stack of media sheets). Further, in some embodiments, the support structure is adapted to simultaneously vibrate at least two of the support structures at different frequencies when activated by the controller.
The “support structure” mentioned above can actually be a single structure or many structures. For example, the support structure can comprise a single structure connected to all of the projections or a plurality of structures, each of which is connected to at least one of the projections. Additionally, the support structure can comprise a cam adapted to move the support structure in a vibrating pattern, a plurality of electric stepper motors, etc. The support structure is adapted to vibrate the projections sufficiently to transfer vibrations from the bottom sheet to the top sheet to aid the media mover in removing only the top sheet and not any sheets adjacent to the top sheet.
These and other features are described in, or are apparent from, the following detailed description.